The long-term objective of the presently proposed line of research is to establish a firm physiological base of understanding for diagnosis and management of speech articulatory disorders. The current research revolves around three fundamental concepts: (1) speech production is characterized by great and as yet largely undefined variability, (2) documentation of (a) adaptive behaviors in response to prosthetically altered speech structure, (b) spontaneous compensatory actions arising from recent physical defect of speech structure, and (c) exploratory activity incident to articulatory shaping procedures may help isolate advantageous and disadvantageous strategies employed, and (3) speech articulatory disorders may be fruitfully interpreted as overt expressions of unsuccessful strategies and executions of complex articulatory motor events. To test the above conceptualizations, a series of experiments have been designed which will generate parallel physiological, acoustical and perceptual data to document variability and change in speech articulation during utterance of selected anterior fricative sounds. These data will be used to help define processes of speech adaptation and compensation and to extract principles that appear to govern change in articulatory proficiency.